Fan and impeller thereof

ABSTRACT

An impeller used in a fan is provided. The impeller includes a hub and a plurality of blades disposed around the hub. The hub has at least one curve-shape surface. A fan comprises a fan frame, an impeller, and a motor. The impeller disposed in the fan frame comprises a hub and a plurality of blades disposed around the hub, wherein the hub has at least one curve-shape surface and an airflow guiding structure disposed on an outer circumference of the hub. The motor is disposed in the impeller for driving the impeller.

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 096111219, filed in Taiwan, Republic of China on Mar. 30, 2007, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a fan and an impeller thereof, and in particular to a fan and the impeller thereof with increased performance.

2. Related Art

The efficiency of a fan is evaluated by the air pressure and air flow that it can generate. To increase the air pressure and air flow, one method is to increase its rotation speed. However, noises come with high-speed rotations.

FIG. 1 is a cross-sectional view of a conventional fan 1. The fan 1 includes a fan frame 10, a motor 11 and an impeller 12.

The impeller 12 includes a hub 121 and several blades 122 disposed around the hub 121. However, since the space inside the fan frame 10 is insufficient, the hub 121 has a vertical structure. When air is guided into the fan via the inlet 101, it is directly guided out via the outlet 102 by the second guiding angle 109 because of the vertical structure of the hub 121. As a result, there is no significant increase in the airflow pressure. Consequently, the conventional fan 1 cannot provide good performance.

SUMMARY OF THE INVENTION

In view of the foregoing, the present invention is to provide an impeller that can increase the air pressure and air flow of a fan.

In addition, the present invention is also to provide a fan that has an airflow guiding structure formed with the hub for decreasing the airflow channel so as to increase the air flow and air pressure thereof.

To achieve the above, the present invention discloses an impeller including a hub and a plurality of blades. The hub has at least one curve-shape surface, and the blades are disposed around the hub. A ratio of an outer diameter of the top surface and an outer diameter of the bottom surface is smaller than 0.45. A tangential angle between the curve-shape surface and the top surface is between 0 and 45 degrees, and an angle between the curve-shape surface and the bottom surface is between 30 and 75 degrees. The curve-shape surface of the hub is continuous or discontinuous. An angle between a horizontal line and a line connecting both ends of the curve-shape surface of the hub is smaller than 70 degrees.

To achieve the above, the present invention also discloses a fan including a fan frame, an impeller and a motor. The impeller is disposed in the fan frame, and the motor is disposed in the impeller for driving the impeller. The impeller includes a hub and a plurality of blades disposed around the hub. The hub has at least one curve-shape surface and an airflow guiding structure disposed on an outer circumference of the hub. The airflow guiding structure and the hub are integrally formed as a single unit. The fan frame includes a connecting element disposed between the fan frame and the base. The connecting element, the fan frame and the base are integrally formed as a single unit. The connecting element includes a plurality of ribs or stationary blades.

As mentioned above, the fan of the present invention utilizes an airflow guiding structure disposed on the hub to shrink the airflow channel, thereby squeezing the airflow to change its flowing speed. Compared with the related art, the airflow speed is increased so that the air flow and air pressure of the fan are both promoted, thereby improving the performance of the fan.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a cross-sectional view of a conventional fan;

FIG. 2 is a cross-sectional view of a fan according to an embodiment of the present invention; and

FIG. 3 is a schematic illustration showing the curves of the air flow and air pressure of the fans of the present invention and the conventional fan.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.

FIG. 2 is a cross-sectional view of a fan according to an embodiment of the present invention. Referring to FIG. 2, a fan 2, which is preferably an axial-flow fan, includes a fan frame 20, an impeller 30 and a motor 40. The impeller 30 and the motor 40 are disposed within the fan frame 20. The fan frame 20 includes a main body 201 with a through hole to form an inlet 21, and an outlet 22. The fan frame can have a roughly square, circular; elliptical or rhombus shape. Furthermore, the fan frame 20 includes a base 202 and at least one connecting element 204. The base 202 is preferably disposed near the outlet 22 of the fan 2. The connecting element 204 is disposed between the main body 201 and the base 202 for supporting the base 202. In this embodiment, the connecting element 204 can be several ribs or stationary blades and is integrally formed with the base 202 and the main body 201 as a single unit. Moreover, the impeller 30 has a hub 301 and several blades 302 disposed around the hub 301. The motor 40 is disposed inside the hub 301. The impeller 30 is disposed on the base 202 of the fan frame 20. The motor 40 drives the impeller 30 to rotate.

It should be noted that to increase the air pressure and air flow of the fan, the impeller 30 having a hub has an airflow guiding structure 303 formed with the outer circumference of the hub 301. The airflow guiding structure can be integrally formed with the hub 301 as a single unit. In this embodiment, the hub 301 of the impeller 30 has a top surface 311 and a bottom surface 312. The outer diameter of the hub 301 increases progressively from the top surface 311 to the bottom surface 312. The blades 302 of the impeller 30 are disposed around the circumference of the airflow guiding structure 303 and the blades 302 extend beyond the airflow guiding structure 303 to cover the base 202. The airflow guiding structure 303 has at least one curve-shape surface that involves a continuous or discontinuous surface. The hub 301 can also have a curve-shape surface, and the airflow guiding structure 303 is disposed on the outer circumference of the hub 301. Due to the design of the impeller 30, the airflow is squeezed by the decreasing airflow channel as it enters the inlet 21 and flows through the airflow guiding structure 303. Therefore, both the airflow speed and pressure can be increased.

The impeller 30 is described with reference to FIG. 2 as follows. The ratio of the outer diameter D1 of the top surface 311 of the hub 301 and the outer diameter D2 of the bottom surface 312 of the hub 301 is smaller than 0.45. The ratio of the outer diameter D1 of the top surface 311 of the hub 301 and the inner diameter D3 of the fan frame 20 is smaller than 0.35. The ratio of the height H1 of the hub 301 and the height H3 of the fan frame 20 is greater than 0.6. The tangential angle θ1 between the airflow guiding structure 303 and the top surface 311 is between 0 and 45 degrees. The angle θ2 between the airflow guiding structure 303 and the bottom surfaced 312 is between 30 and 75 degrees. The line connecting both ends of the curved surface of the airflow guiding structure 303 and the horizontal line have an angle θ3 smaller than 70 degrees.

When the motor 40 operates and drives the impeller 30 to rotate, the blades 302 around the hub 301 rotate and generate a pressure difference between the fan 2 and the external environment. The main body 201 has a first guiding angle 208 and a second guiding angle 209 at the inlet 21 and the outlet 22, respectively. The first guiding angle 208 and the second guiding angle 209 are formed along the inclined planes for guiding more airflow in and out. Therefore, air enters via the inlet 21, goes into the fan frame, guided by the guiding angle, and flows toward the outlet 22. Since the airflow guiding structure 303 is a continuous curved surface, the shrinking airflow channel squeezes the airflow and speeds it up as it flows through the airflow guiding structure 303. At the same time, the airflow pressure increases.

FIG. 3 is a schematic illustration showing the curves of the air flow and air pressure of the fan of the present invention and the conventional fan. Experimental data show that the fan of the present invention can effectively increase the air flow and air pressure. For example, at the same air flow, the maximum air pressure of the present invention is about 1.4 times larger than the prior art. At the same air pressure, the maximum air flow of the present invention is increased about 1.15 times.

In summary, the fan of the present invention has the following advantages. Using the disclosed airflow guiding structure disposed on the hub, the shrinking airflow channel squeezes the airflow to change its flowing speed. Compared with the related art, the airflow speed is increased so that the air flow and air pressure of the fan are both promoted, thereby improving the performance of the fan.

Although the present invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the present invention. 

1. An impeller, comprising: a hub comprising an airflow guiding structure formed with an outer circumference of the hub; and a plurality of blades disposed around the hub.
 2. The impeller of claim 1, wherein the hub has a top surface and a bottom surface, and an outer diameter of the hub increases progressively from the top surface to the bottom surface.
 3. The impeller of claim 2, wherein a ratio of the outer diameter of the top surface and the outer diameter of the bottom surface is smaller than 0.45.
 4. The impeller of claim 4, wherein the airflow guiding structure comprises at least one curve-shape surface.
 5. The impeller of claim 4, wherein a tangential angle between the curve-shape surface and the top surface is between 0 and 45 degrees.
 6. The impeller of claim 4, wherein an angle between the curve-shape surface and the bottom surface is between 30 and 75 degrees.
 7. The impeller of claim 4, wherein an angle between a horizontal line and a line connecting both ends of the curve-shape surface of the hub is smaller than 70 degrees.
 8. A fan, comprising: a fan frame; an impeller disposed in the fan frame, and comprising a hub and a plurality of blades disposed around the hub, wherein the hub comprises an airflow guiding structure formed with an outer circumference of the hub; and a motor disposed in the fan frame for driving the impeller to rotate.
 9. The fan of claim 8, wherein the airflow guiding structure and the hub are integrally formed as a single unit.
 10. The fan of claim 8, wherein the hub has a top surface and a bottom surface, and an outer diameter of the hub increases progressively from the top surface to the bottom surface.
 11. The fan of claim 10, wherein a ratio of the outer diameter of the top surface and the outer diameter of the bottom surface is smaller than 0.45 or a ratio of the outer diameter of the top surface of the hub and an inner diameter of the fan frame is smaller than 0.35.
 12. The fan of claim 10, wherein a tangential angle between the airflow guiding structure and the top surface of the hub is between 0 and 45 degrees or an angle between the airflow guiding structure and the bottom surface of the hub is between 30 and 75 degrees.
 13. The fan of claim 8, wherein a ratio of a height of the hub and a height of the fan frame is greater than 0.6.
 14. The fan of claim 8, wherein the airflow guiding structure comprises at least one curve-shape surface.
 15. The fan of claim 14, wherein an angle between a horizontal line and a line connecting both ends of the curve-shape surface of the hub is smaller than 70 degrees.
 16. The fan of claim 8, wherein the fan flame comprises a main body, and the main body has a first guiding angle and a second guiding angle at the inlet and the outlet respectively, and the first guiding angle and the second guiding angle are formed along the inclined plane for guiding more airflow in and out.
 17. The fan of claim 16, wherein the fan frame comprises a base and a plurality of connecting elements disposed between the main body and the base.
 18. The fan of claim 17, wherein the blades extend beyond the airflow guiding structure to cover the base.
 19. The fan of claim 17, wherein the connecting element, the main body, and the base are integrally formed as a single unit.
 20. The fan of claim 17, wherein the connecting elements comprise a plurality of ribs or stationary blades. 